Understanding the Subseasonal Modulation of Moisture Transport over the Indian Monsoon Domain Journal Article uri icon

Overview

abstract

  • The subseasonal modes of integrated water vapor transport (IVT) over the; Indian Summer Monsoon (ISM) domain were examined and their association; with different modes of ISM precipitation was analyzed during boreal; summer seasons from 1979-2018. The IVT over the monsoon domain was found; to exhibit significant variability in the intraseasonal (20-60 days),; quasi-biweekly (10-20 days), and synoptic (3-10 days) time scales. The; intraseasonal IVT mode is dominant between 0-20°N and reflects the; fluctuations of the low-level jet stream. The quasi-biweekly and; synoptic-scale IVT variability dominates over the Bay of Bengal and the; Indo-Gangetic plain. The intraseasonal IVT mode is the most dominant and; it is found to influence the higher frequency subseasonal IVT modes.; Meanwhile, large-scale factors such as the El Niño Southern Oscillation; (ENSO) and the Indian Ocean Dipole (IOD) were found to modulate the; intraseasonal IVT mode and negatively impact the monsoon. Lead-lag; correlation analysis between the subseasonal precipitation and IVT modes; suggests that the IVT anomalies are driven by the subseasonal convective; anomalies and associated changes in atmospheric circulation. Since; moisture supply from adjoining oceanic regions is fundamental for; monsoon precipitation, there is a general tendency to attribute the; variability/trends in precipitation to changes in moisture transport.; Our analysis of the subseasonal modes of IVT indicates that such; inferences may be misrepresentative, as the monsoon diabatic heating in; itself is a strong driver of monsoon circulation and moisture transport.

publication date

  • July 2, 2020

has restriction

  • closed

Date in CU Experts

  • November 7, 2020 9:01 AM

Full Author List

  • Neena JM; Dilip V; Subramanian A

author count

  • 3

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